Re: [PATCH 3/5] mm: export zap_page_range_single and list_lru_add/del

[Alice Ryhl <aliceryhl@google.com>]

On Thu, Feb 05, 2026 at 12:10:38PM +0000, Lorenzo Stoakes wrote:
> On Thu, Feb 05, 2026 at 11:58:00AM +0000, Alice Ryhl wrote:
> > On Thu, Feb 05, 2026 at 12:43:03PM +0100, David Hildenbrand (arm) wrote:
> > > On 2/5/26 12:29, Lorenzo Stoakes wrote:
> > > > On Thu, Feb 05, 2026 at 10:51:28AM +0000, Alice Ryhl wrote:
> > > > >   bool list_lru_del_obj(struct list_lru *lru, struct list_head *item)
> > > > >   {
> > > > > diff --git a/mm/memory.c b/mm/memory.c
> > > > > index da360a6eb8a48e29293430d0c577fb4b6ec58099..64083ace239a2caf58e1645dd5d91a41d61492c4 100644
> > > > > --- a/mm/memory.c
> > > > > +++ b/mm/memory.c
> > > > > @@ -2168,6 +2168,7 @@ void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
> > > > >   	zap_page_range_single_batched(&tlb, vma, address, size, details);
> > > > >   	tlb_finish_mmu(&tlb);
> > > > >   }
> > > > > +EXPORT_SYMBOL(zap_page_range_single);
> > > >
> > > > Sorry but I don't want this exported at all.
> > > >
> > > > This is an internal implementation detail which allows fine-grained control of
> > > > behaviour via struct zap_details (which binder doesn't use, of course :)
> > >
> > > I don't expect anybody to set zap_details, but yeah, it could be abused.
> > > It could be abused right now from anywhere else in the kernel
> > > where we don't build as a module :)
> > >
> > > Apparently we export a similar function in rust where we just removed the last parameter.
> >
> > To clarify, said Rust function gets inlined into Rust Binder, so Rust
> > Binder calls the zap_page_range_single() symbol directly.
> 
> Presumably only for things compiled into the kernel right?

No, building Rust Binder with =m triggers this error for me:

ERROR: modpost: "zap_page_range_single" [drivers/android/binder/rust_binder.ko] undefined!

Alice